I have the ‘more’ option enabled.
All works fine generally except a specific situation.
Mouse over ‘more’ to reveal extra items
If top level item is not valid link but ‘#’ instead then OK
If top level item is valid URL, when clicked, ‘more’ items appear on second line under main horizontal menu.
If brower window is expanded or reduced slightly it disappears – but it is annoying!
It does not seem to be an issue whe on Ipad etc.
Hopefully it is obvious to you what may be going on.